I'd suggest starting at Chapter 95. It smoothly picks up where Season 3 leaves off and continues the exciting plot. There are new characters and challenges introduced that will keep you engaged.
You can start from the chapter that corresponds to where season 2 ended. Usually, you can find this information on manga-related forums or from fellow fans.
The best places to read the Demon Slayer manga after the anime are dedicated manga apps like Manga Rock or Manga Plus. These offer a wide range of chapters and often have good reading experiences. You could also look for digital versions on the publisher's website.
There are a few novels that I can recommend to you. They are all stories about being reborn as a Demon Slayer. The first was "Rebirth of the Sea of Laws, I Slay Demons in the Human World" and "Rebirth of Slaying Demons, I Actually Became a Demon Venerable?" They all focused on slaying demons and told the story of the protagonist becoming a demon slayer after his rebirth. In addition, there was also "Xu Xian's Demon-slaying Daily Life (Demonic Meow)" and "Black Moonlight of the Rebirth of the Demon Lord," which also involved the demon-slaying plot. These novels all have different styles and storylines. You can choose to read them according to your preferences.
Definitely! Demon Slayer started as a manga. It's known for its compelling plot and well-developed characters. The manga provides the foundation for the success of the anime adaptation.